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Niall D Ferguson

Publications and source records attributed to Niall D Ferguson.

At least 19 recordsLinked to original sources
PubMed2006

Epidemiology of acute lung injury and acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a heterogeneous disorder that may be triggered by myriad etiologies (both pulmonary and extrapulmonary). Mortality rates for ARDS range from 30 to 75%, and most deaths are a consequence of multiorgan failure (MOF). Since the sentinel description of ARDS in 1967, criteria for the diagnosis of this entity were refined. In 1992, diagnostic criteria for ARDS were published in an American-European Consensus Conference and the term ACUTE LUNG INJURY (ALI) was adopted to encompass patients with a spectrum of less severe forms of the same pathological entity. This review discusses limitations of various criteria utilized to diagnosis ARDS and ALI, and why some criteria may be problematic when designing clinical trials. Also discussed are the myriad causes of ARDS, incidence, epidemiology, mortality, and factors that influence outcome.

Humans↗
PubMed2006

Lung-protective ventilation in neurosurgical patients.

PURPOSE OF REVIEW: Concepts of ventilator-induced lung injury have revolutionized our approach to the ventilatory management of patients with acute lung injury and acute respiratory distress syndrome over the past 10 years. The extension of these principles to patients with brain injuries is challenging, as many of them are out of keeping with usual brain-protective management. RECENT FINDINGS: Many patients with acute lung injury or acute respiratory distress syndrome and an acute brain injury may in fact be managed safely within the confines of a lung-protective strategy. Elevated levels of positive end-expiratory pressure in head-injured patients with acute lung injury or acute respiratory distress syndrome also appear to be safe, particularly when the level is set below that of the intracranial pressure, when patients have a low respiratory system compliance, or when positive end-expiratory pressure results in significant lung volume recruitment. Several novel therapies to minimize ventilator-induced lung injury are currently in the early stages of investigation in neurosurgical patients. SUMMARY: In many patients with brain injuries and acute lung injury the goals of lung protection can be achieved without threatening cerebral perfusion. In patients with more refractory raised intracranial pressure the optimal balance between brain and lung is not well established. Further research is needed on lung-protective strategies in this vulnerable population.

Brain Injuries↗
PubMed2006

Outcomes of interfacility critical care adult patient transport: a systematic review.

INTRODUCTION: We aimed to determine the adverse events and important prognostic factors associated with interfacility transport of intubated and mechanically ventilated adult patients. METHODS: We performed a systematic review of MEDLINE, CENTRAL, EMBASE, CINAHL, HEALTHSTAR, and Web of Science (from inception until 10 January 2005) for all clinical studies describing the incidence and predictors of adverse events in intubated and mechanically ventilated adult patients undergoing interfacility transport. The bibliographies of selected articles were also examined. RESULTS: Five studies (245 patients) met the inclusion criteria. All were case-series and two were prospective in design. Due to the paucity of studies and significant heterogeneity in study population, outcome events, and results, we synthesized data in a qualitative manner. Pre-transport severity of illness was reported in only one study. The most common indication for transport was a need for investigations and/or specialist care (three studies, 220 patients). Transport modalities included air (fixed or rotor wing; 66% of patients) and ground (31%) ambulance, and commercial aircraft (3%). Transport teams included a physician in three studies (220 patients). Death during transfer was rare (n = 1). No other adverse events or significant therapeutic interventions during transport were reported. One study reported a 19% (28/145) incidence of respiratory alkalosis on arrival and another study documented a 30% overall intensive care unit mortality, while no adverse events or outcomes were reported after arrival in the three other studies. CONCLUSION: Insufficient data exist to draw firm conclusions regarding the mortality, morbidity, or risk factors associated with the interfacility transport of intubated and mechanically ventilated adult patients. Further study is required to define the risks and benefits of interfacility transfer in this patient population. Such information is important for the planning and allocation of resources related to transporting critically ill adults.

Adult↗
PubMed2006

Risk factors for extubation failure in patients following a successful spontaneous breathing trial.

BACKGROUND: To assess the factors associated with reintubation in patients who had successfully passed a spontaneous breathing trial. METHODS: We used logistic regression and recursive partitioning analyses of prospectively collected clinical data from adults admitted to ICUs of 37 hospitals in eight countries, who had undergone invasive mechanical ventilation for > 48 h and were deemed ready for extubation. RESULTS: Extubation failure occurred in 121 of the 900 patients (13.4%). The logistic regression analysis identified the following associations with reintubation: rapid shallow breathing index (RSBI) [odds ratio (OR), 1.009 per unit; 95% confidence interval (CI), 1.003 to 1.015]; positive fluid balance (OR, 1.70; 95% CI, 1.15 to 2.53); and pneumonia as the reason for initiating mechanical ventilation (OR, 1.77; 95% CI, 1.10 to 2.84). The recursive partitioning analysis allowed the separation of patients into different risk groups for extubation failure: (1) RSBI of > 57 breaths/L/min and positive fluid balance (OR, 3.0; 95% CI, 1.8 to 4.8); (2) RSBI of < 57 breaths/L/min and pneumonia as reason for mechanical ventilation (OR, 2.0; 95% CI, 1.1 to 3.6); (3) RSBI of > 57 breaths/L/min and negative fluid balance (OR, 1.4; 95% CI, 0.8 to 2.5); and (4) RSBI of < 57 breaths/L/min (OR, 1 [reference value]). CONCLUSIONS: Among routinely measured clinical variables, RSBI, positive fluid balance 24 h prior to extubation, and pneumonia at the initiation of ventilation were the best predictors of extubation failure. However, the combined predictive ability of these variables was weak.

Aged↗
PubMed2005

Is it time to increase the frequency of use of high-frequency oscillatory ventilation?

In this issue of Critical Care, Bollen and colleagues present the results of a multicentre randomised controlled trial, comparing high-frequency oscillatory ventilation with conventional ventilation as the primary ventilation mode for adults with acute respiratory distress syndrome. The study was stopped early after recruiting only 61 patients because of declining enrolment, and although no differences were detected in any primary or secondary endpoint, this trial only had sufficient power to detect extreme differences in outcomes between groups. This editorial attempts to put these results in context with previous work and highlights challenges to be addressed in future studies.

Adult↗
PubMed2005

Development of a clinical definition for acute respiratory distress syndrome using the Delphi technique.

PURPOSE: The objective of this study is to describe the implementation of formal consensus techniques in the development of a clinical definition for acute respiratory distress syndrome. MATERIALS AND METHODS: A Delphi consensus process was conducted using e-mail. Sixteen panelists who were both researchers and opinion leaders were systematically recruited. The Delphi technique was performed over 4 rounds on the background of an explicit definition framework. Item generation was performed in round 1, item reduction in rounds 2 and 3, and definition evaluation in round 4. Explicit consensus thresholds were used throughout. RESULTS: Of the 16 panelists, 11 actually participated in developing a definition that met a priori consensus rules on the third iteration. New incorporations in the Delphi definition include the use of a standardized oxygenation assessment and the documentation of either a predisposing factor or decreased thoracic compliance. The panelists rated the Delphi definition as acceptable to highly acceptable (median score, 6; range, 5-7 on a 7-point Likert scale). CONCLUSIONS: We conclude that it is feasible to consider using formal consensus in the development of future definitions of acute respiratory distress syndrome. Testing of sensibility, reliability, and validity are needed for this preliminary definition; these test results should be incorporated into future iterations of this definition.

Delphi Technique↗
PubMed2005

Airway pressures, tidal volumes, and mortality in patients with acute respiratory distress syndrome.

OBJECTIVE: To determine the usual practice for setting tidal volume and other ventilatory parameters in patients with acute respiratory distress syndrome (ARDS) in the late 1990s and to determine the independent effects of these practices on intensive care unit mortality. DESIGN: Subanalysis of a prospective observational study. Multivariable logistic regression was used to analyze the effects of ventilatory management on mortality. SETTING: A total of 361 intensive care units in 20 countries in March 1998. PATIENTS: A total of 467 mechanically ventilated patients with ARDS. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The mean tidal volume used in the first week of ARDS was 8.8 mL/kg measured body weight, and there was great variability in these tidal volumes (sd = 2.0). Tidal volumes were significantly lower in patients with (n = 265) than without (n = 202) a recorded plateau pressure (8.6 vs. 9.1 mL/kg, p = .01). The overall intensive care unit mortality rate was 60.2%. In addition to the strong influence of organ failures and higher levels of inspired oxygen, late-onset ARDS (onset after >48 hrs of mechanical ventilation; odds ratio, 2.09) was independently associated with mortality. In addition, lower levels of positive end-expiratory pressure were independently associated with higher mortality (odds ratio, 0.91; 1 cm of H2O increments). Neither inspiratory pressures nor tidal volumes were independently associated with mortality, and there was no evidence of increased mortality with the use of lower inspiratory pressures. CONCLUSIONS: This descriptive study demonstrated considerable interpatient variability in tidal volumes during the study period. In addition to traditional prognostic indicators, timing of ARDS onset and the use of low levels of positive end-expiratory pressure or no positive end-expiratory pressure during the first week may adversely influence outcome in ARDS patients.

Adult↗
PubMed2005

Combining high-frequency oscillatory ventilation and recruitment maneuvers in adults with early acute respiratory distress syndrome: the Treatment with Oscillation and an Open Lung Strategy (TOOLS) Trial pilot study.

OBJECTIVE: To determine the safety, feasibility, and lung-recruitment efficacy of an explicit ventilation protocol combining high-frequency oscillatory ventilation and recruitment maneuvers. DESIGN: Prospective, multiple-center, single-intervention pilot study. SETTING: Four university-affiliated intensive care units. PATIENTS: Twenty-five patients with early acute respiratory distress syndrome and severe oxygenation failure. INTERVENTIONS: Patients were transitioned from standardized conventional ventilation to high-frequency oscillatory ventilation beginning with an initial cycle of up to three sustained inflation recruitment maneuvers (40 cm H2O x 40 secs), followed by a decremental titration of Fio2 and then mean airway pressure. Recruitment maneuvers were repeated for hypoxemia and routinely at least twice daily if the Fio2 was >0.4. A specific protocol was used for weaning high-frequency oscillatory ventilation, for transitioning to conventional ventilation, and for judging intolerance of conventional ventilation whereby patients should be put back on high-frequency oscillatory ventilation. MEASUREMENTS AND MAIN RESULTS: Patients (median [interquartile range] Acute Physiology and Chronic Health Evaluation II, 24 [19-32]; age, 50 [41-64]) were enrolled after 13 (range, 6-51) hrs of conventional ventilation. Following the initial cycle of recruitment, the mean (+/-sd) Pao2/Fio2 increased significantly compared with standardized conventional ventilation (200 +/- 117 vs. 92 +/- 36 mm Hg, p < .001). After a mean of 12 hrs of high-frequency oscillatory ventilation, the mean Fio2 was significantly reduced compared with prestudy levels (0.5 +/- 0.2 vs. 0.9 +/- 0.1, p < .001). A median of seven (four to 11) recruitment maneuvers was performed per patient over the study period, with only eight of 244 (3.3%) being aborted. Six of 19 patients transitioned to conventional ventilation (32%) were deemed intolerant and were switched back to high-frequency oscillatory ventilation. Protocol adherence was excellent with documented rates >90%. CONCLUSIONS: The combination of high-frequency oscillatory ventilation and recruitment maneuvers resulted in rapid and sustained improvement in oxygenation, likely through lung recruitment. This explicit high-frequency oscillatory ventilation protocol appears well tolerated, feasible, and physiologically sound.

Adult↗
PubMed2005

Nursing and infection-control issues during high-frequency oscillatory ventilation.

OBJECTIVES: To review the specific nursing and infection-control issues that arise during the care of patients receiving high-frequency oscillatory ventilation (HFOV). DATA SOURCE: Published articles, governmental guidelines, and hospital procedures and practices. DATA SUMMARY: Nurses, respiratory therapists, and other clinicians caring for patients receiving HFOV need to be aware of specific differences in patient assessment, including close observation for symmetric chest-wall vibrations. In addition, management of sedation with or without neuromuscular blockade and effective communication with the patients are essential nursing skills needed with the use of HFOV. From an infection-control standpoint, HFOV is considered a high-risk respiratory procedure because of the inability to effectively filter all respiratory secretions. Appropriate infection-control precautions, including patient location and use of personal protective equipment, need to be considered when implementing HFOV in the intensive care unit. CONCLUSIONS: Important infection-control and nursing issues exist that are specific to the use of HFOV. These issues should be addressed with appropriate staff education before the implementation of HFOV in an intensive care unit.

High-Frequency Ventilation↗
PubMed2005

Acute respiratory distress syndrome: underrecognition by clinicians and diagnostic accuracy of three clinical definitions.

OBJECTIVE: To determine and compare the diagnostic accuracy of three clinical definitions of acute respiratory distress syndrome (ARDS): (1) the American-European consensus conference definition; (2) the lung injury score; and (3) a recently developed Delphi definition. A second objective was to determine the accuracy of clinical diagnoses of ARDS made in daily practice. DESIGN: Independent comparison of autopsy findings with the daily status of clinical definitions, constructed with data abstracted retrospectively from medical records. SETTING: Tertiary intensive care unit. PATIENTS: One hundred thirty-eight patients from the period 1995 through 2001 who were autopsied after being mechanically ventilated. INTERVENTIONS: Clinical ARDS diagnoses were determined daily without knowledge of autopsy results. Charts were reviewed for any mention of ARDS in the clinical notes. Autopsies were reviewed independently by two pathologists for the presence of diffuse alveolar damage. The sensitivity and specificity of the definitions were determined with use of diffuse alveolar damage at autopsy as the reference standard. MEASUREMENTS AND MAIN RESULTS: Diffuse alveolar damage at autopsy was documented in 42 of 138 cases (30.4%). Only 20 of these 42 patients (47.6%) had any mention of ARDS in their chart. Sensitivities and specificities (95% confidence intervals) were as follows: American-European definition, 0.83 (0.72-0.95), 0.51 (0.41-0.61); lung injury score, 0.74 (0.61-0.87), 0.77 (0.69-0.86); and Delphi definition, 0.69 (0.55-0.83), 0.82 (0.75-0.90). Specificity was significantly higher for both the lung injury score and Delphi definition than for the American-European definition (p < .001 for both), whereas comparisons of sensitivity, which was higher for the American-European definition, were not significantly different (p = .34 and p = .07, respectively). CONCLUSIONS: Acute respiratory distress syndrome appears underrecognized by clinicians in patients who die with this syndrome. In this population, the specificities of existing clinical definitions vary considerably, which may be problematic for clinical trials.

Aged↗
PubMed2004

Comparison of clinical criteria for the acute respiratory distress syndrome with autopsy findings.

BACKGROUND: The American-European Consensus Conference definition for the acute respiratory distress syndrome (ARDS) has never been validated. OBJECTIVE: To compare clinical criteria for ARDS with autopsy findings. DESIGN: Independent comparison of autopsy findings with clinical characteristics retrospectively abstracted from medical records. SETTING: Tertiary medical-surgical intensive care unit. PARTICIPANTS: 382 patients who underwent clinical autopsy. MEASUREMENTS: Sensitivity, specificity, and likelihood ratios for clinical criteria were calculated in 3 cohorts by using diffuse alveolar damage at autopsy as the reference standard. The 3 cohorts were 1) all patients, 2) patients with any risk factor for ARDS, and 3) patients who were separated according to their pulmonary or extrapulmonary risk factors. RESULTS: 127 patients (33%) met the clinical criteria, and 112 (29%) had diffuse alveolar damage. In all patients, the sensitivity of the clinical definition was 75% (95% CI, 66% to 82%) and the specificity was 84% (CI, 79% to 88%). In 284 patients with risk factors, the sensitivity was 76% (CI, 67% to 83%) and the specificity was 75% (CI, 68% to 81%). Compared with patients with pulmonary risk factors, patients with extrapulmonary risk factors had significantly higher sensitivity (61% vs. 85%; P = 0.009) and the specificity did not statistically significantly differ (69% vs. 78%; P > 0.2). LIMITATIONS: Only patients who died and underwent autopsy could be included in this study, so these results may not apply to less severe cases of ARDS. CONCLUSIONS: In a series of autopsy patients, the accuracy of the American-European Consensus Conference definition of ARDS was only moderate. The definition was more accurate for patients with extrapulmonary risk factors than for patients with pulmonary risk factors.

Aged↗
PubMed2004

Noninvasive positive-pressure ventilation for respiratory failure after extubation.

BACKGROUND: The need for reintubation after extubation and discontinuation of mechanical ventilation is not uncommon and is associated with increased mortality. Noninvasive positive-pressure ventilation has been suggested as a promising therapy for patients with respiratory failure after extubation, but a single-center, randomized trial recently found no benefit. We conducted a multicenter, randomized trial to evaluate the effect of noninvasive positive-pressure ventilation on mortality in this clinical setting. METHODS: Patients in 37 centers in eight countries who were electively extubated after at least 48 hours of mechanical ventilation and who had respiratory failure within the subsequent 48 hours were randomly assigned to either noninvasive positive-pressure ventilation by face mask or standard medical therapy. RESULTS: A total of 221 patients with similar baseline characteristics had been randomly assigned to either noninvasive ventilation (114 patients) or standard medical therapy (107 patients) when the trial was stopped early, after an interim analysis. There was no difference between the noninvasive-ventilation group and the standard-therapy group in the need for reintubation (rate of reintubation, 48 percent in both groups; relative risk in the noninvasive-ventilation group, 0.99; 95 percent confidence interval, 0.76 to 1.30). The rate of death in the intensive care unit was higher in the noninvasive-ventilation group than in the standard-therapy group (25 percent vs. 14 percent; relative risk, 1.78; 95 percent confidence interval, 1.03 to 3.20; P=0.048), and the median time from respiratory failure to reintubation was longer in the noninvasive-ventilation group (12 hours vs. 2 hours 30 minutes, P=0.02). CONCLUSIONS: Noninvasive positive-pressure ventilation does not prevent the need for reintubation or reduce mortality in unselected patients who have respiratory failure after extubation.

Aged↗
PubMed2004

Pro/con clinical debate: tracheostomy is ideal for withdrawal of mechanical ventilation in severe neurological impairment.

Most clinical trials on the topic of extubation have involved patients outside the neurological intensive care unit. As a result, in this area clinicians are left with little evidence on which to base their decision making. Although tracheostomies are increasingly common procedures, they are not without complications and costs, and hence a decision to perform them should not be taken lightly. In this issue of Critical Care two groups debate the merits of tracheostomy before extubation in a patient with neurological impairment. What becomes very clear is the need for more high quality data for this common clinical problem.

Brain Injuries↗